Hammerhead Worms can be controlled

Published 10:37 am Thursday, September 16, 2021

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Across the South an invasive species is showing up in gardens. Hammerhead worms have had many gardeners scratching their heads throughout the summer months. While it has an appearance similar to a hammerhead shark, it is also an aggressive and cannibalistic worm that is difficult to get rid of. Katelyn Kesheimer, an Alabama Extension entomologist, shares some background information to put your mind at ease about these hammerhead worms.

About Hammerhead Worms

“Hammerhead worms are native to tropical and subtropical environments,” Kesheimer said. “It is likely they hitchhiked to the United States on the roots of horticultural plants and may continue to be accidentally spread across the country on roots or soil of potted plants. Regardless of how they got here, it appears they are here to stay.”

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Hammerhead worms are predators, meaning the worms will feed on other small creatures in the landscape. These include the beneficial and native earthworms.

While they are aggressive, the number of hammerhead worms has not reached high enough numbers to impact the earthworm populations yet. The worms do have an up-and-coming predator, amphibians. Some amphibians have already been feeding on these worms. Since the worms are cannibalistic, this also helps to keep the population in check.

Where are they found?

Hammerhead worms thrive in hot, humid environments. This summer in Alabama has been perfect for these worms and is likely the reason many homeowners are seeing them out and about.

“They do show up after a rain, so that is probably why we’ve been seeing some lately,” Kesheimer said. “But they will likely not be around very often once we get a hot, dry spell.”

All of the rain we have had this summer is why we are seeing them more than usual, but she is confident that as long as the rain holds off for a while in these hot dog days of summer the population will shrink substantially. As long as there is adequate moisture, hammerhead worms will stick around.

Common hiding places for them include leaf litter or under rocks, logs or shrubs. Kesheimer said one place hammerhead worms may stick around is in greenhouses. The high temperature and moisture levels in greenhouses make them a good environment for these worms.

What can you do?

“The thing to keep in mind is that these worms reproduce asexually, so if you are trying to get rid of them, cutting them in half will only make more worms,” Kesheimer said. “They also possess a toxin and we don’t have information on how harmful it is to humans, so I would avoid touching the worms if possible.”

If there is a real infestation in the lawn or garden Kesheimer advises sprinkling salt directly on the worm. Another easy home remedy is vinegar or citrus oil sprayed directly on the worm. But keep in mind, if you apply large amounts of salt or vinegar to the landscape, it can harm vegetation, as well as our native, beneficial earthworms.

While gardeners might be able to get them out of the garden, these hammerhead worms appear to be here to stay.